Nozzle piece for a handpiece of a dental apparatus

FIELD OF THE INVENTION

The present invention relates to a nozzle piece for a head portion of a handpiece of a dental abrasive blasting apparatus.

BACKGROUND OF THE INVENTION

A prior art nozzle piece of the kind as herein referred comprises in general an inner discharge nozzle for discharging a mixture of a gaseous carrier medium and an abrasive dental powder as supplied by an associated first supply duct of a gripping member which is connected at an end with the head portion of a handpiece. The nozzle piece further comprises a concentrically arranged outer discharge nozzle for discharging a fluid which is supplied by an associated second supply duct of the gripping member. Nozzle pieces of this kind are disclosed for example in U.S. Pat. Nos. 4,174,571; 4,412,402 and 4,676,749 in combination with a dental abrasive blasting apparatus which comprises a powder reservoir inside of a housing of the apparatus for storing the dental powder. The nozzle piece is fixed to the one end of two tubings which directly connect with inner and outer discharge nozzles of the nozzle piece and which at their opposite end are fixed on a head piece of a gripping sleeve of the handpiece. The two tubings extend in parallel with respect to a longitudinal axis of the handpiece and are running straight or under an angle and sometimes also along a curved path towards the discharge nozzles of the nozzle piece. By these different paths of the two tubings respective different discharge angles are provided for concentric discharge openings of the inner and outer discharge nozzles which have a common central axis with respect to the longitudinal axis of the handpiece. The discharge angle is usuangle is usually in the range of 60° or more. With the provision of a discharge angle of this range any visual contact with the exit of the working jet from the discharge openings of the two discharge nozzles at the tip of the handpiece is not at all taken into consideration and it is instead only intended to reach an optimum manipulation of the handpiece for securely guiding the working jet over the preparation field of the teeth in the course of an abrasive dental treatment. The same strategy may also be recognised for dental handpieces of the kind comprising an integrated powder reservoir as for example described in U.S. Pat. No. 4,776,794 and having also a nozzle piece with inner and outer discharge nozzles for discharging a working jet over a preparation field of the teeth.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a nozzle piece for a handpiece of a dental abrasive blasting apparatus which may be produced in a more simple and more inexpensive manner and which will be designed for allowing some supplemental optimization for a practical handling of the handpiece.

The present invention accordingly provides a nozzle piece which is characterised by the features as outlined in the claims.

A nozzle piece in accordance with the present invention secures a shortening of the overall length of the handpiece by the incorporation of the curved surfaces in accordance with the definition for the gripping member of the nozzle piece since thereby the visual contact with the actual preparation field of the teeth during a dental treatment is now substantially improved. The curvature as defined for the closed surface of the gripping member may be designed under ergonomic viewpoints. Different designs of the nozzle piece may also be taken into consideration especially in such a case when in accordance with an overall preferred embodiment of the present invention the gripping member comprises a metallic or plastic injection moulded part. With the provision of such an injection moulded part the gripping member could be provided at the same time with first and second bores defining the first and second supply ducts which are associated with the two discharge nozzles of the nozzle piece. At least the inner discharge nozzle would then be completed with a discharge tube which will be inserted into the associated inner bore in such a manner that the discharge opening of this discharge tube will protrude over the discharge opening of a larger diameter of the outer discharge nozzle as provided by its associated bore. A nozzle piece according to the present invention may be cleaned most easily and may be produced with low costs so that different discharge angles for the working jet with different design parameters can be envisaged all under the common aspect of optimizing the visual contact with the preparation field of the teeth.

Other objects, features and advantages of the present invention will become apparent from reading the following description of a preferred embodiment of a nozzle piece according to the present invention.

BRIEF DESCRIPTION OF THE DRAWING

<figref idref="DRAWINGS">FIG. 1</figref> is a longitudinal sectional view of the head portion of a handpiece comprising a nozzle piece in accordance with the present invention,

<figref idref="DRAWINGS">FIG. 2</figref> shows the encircled detail X of <figref idref="DRAWINGS">FIG. 1</figref> in a larger scale.

<figref idref="DRAWINGS">FIG. 3</figref> shows the encircled detail X of <figref idref="DRAWINGS">FIG. 1</figref> according to a second embodiment of the present invention.

<figref idref="DRAWINGS">FIG. 4</figref> is a perspective view of the head portion shown in FIG. <b>1</b> and illustrated true to scale.

<figref idref="DRAWINGS">FIG. 5</figref> is a cross-sectional detail showing a preferred embodiment of a plug-in connection.

DETAILED DESCRIPTION

<figref idref="DRAWINGS">FIG. 1</figref> illustrates a gripping sleeve <b>1</b> which forms the head portion of a handpiece of a dental abrasive blasting apparatus for example of the kind as more generally described in U.S. Pat. No. 4,492,575 to which reference may therefore be made for further details of the following description. The gripping sleeve <b>1</b> has a nozzle piece <b>2</b> which is exchangeably arranged on its forward end for providing a working jet when a abrasive dental treatment is applied.

The nozzle piece <b>2</b> comprises a metallic or plastic injection moulded part and has a gripping member <b>3</b> the closed surface of which is provided by definition with a curvature mainly in respect to a definite longitudinal axis <b>4</b> of the handpiece and also with respect to a central axis <b>5</b> of a jet arrangement of the jet piece <b>2</b>. The central axis <b>5</b> defines a discharge angle of a working jet with respect to the definite longitudinal axis <b>4</b> of the handpiece.

As illustrated in more detail in <figref idref="DRAWINGS">FIG. 2</figref> the jet arrangement of the nozzle piece <b>2</b> comprises an inner discharge nozzle <b>6</b> for discharging a mixture of a gaseous carrier medium, namely compressed air in general, and an abrasive dental powder. It further comprises a concentrically arranged outer discharge nozzle for discharging a fluid which in general is water. The working jet is accordingly composed of a mixture of air and powder as supplied by an associated first supply duct <b>8</b> and of water as supplied by an associated second supply duct <b>9</b> whereby the water jet which is discharged from the outer discharge nozzle <b>7</b> surrounds the air and powder jet which is discharged from the inner discharge nozzle <b>6</b>. The working jet which is composed of these components will be directed towards a preparation field of the teeth during an abrasive dental treatment.

The two supply ducts <b>8</b> and <b>9</b> of the two discharge nozzles <b>6</b> and <b>7</b> comprise stepped bores extending in parallel and directed under an angle with respect to the longitudinal axis <b>4</b> of the handpiece which differs from 90°. The larger diameter at the proximal end of these stepped bores serves a plug-in connection of an associated connecting line <b>10</b> and <b>11</b> connected with the two supply ducts for supplying the nozzle piece with the air and powder mixture and with water. The two discharge nozzles of the nozzle piece <b>2</b> also comprise bores whereby the inner discharge nozzle <b>6</b> is completed with a discharge tube <b>12</b> which is inserted into the associated inner bore. The discharge tube <b>12</b> has a slanted cut at its distal end <b>13</b> which protrudes into the bore of the associated supply duct <b>8</b> so that with this slanted cut of the discharge tube <b>12</b> a substantially low loss directional diversion of the air and powder mixture is obtained which is further transmitted to the discharge tube <b>12</b> the discharge opening of which protrudes over the surrounded discharge opening of the outer discharge nozzle. The discharge angle of the working jet which is discharged from a thusly designed nozzle piece is in the range of about 90° with respect to the definite longitudinal axis <b>4</b> of the handpiece in case of the embodiment illustrated in FIG. <b>2</b> and it is in the range of about 120° for the embodiment illustrated in FIG. <b>3</b>.

The gripping member <b>3</b> has a closed surface which by definition is provided with such a curvature that the discharge openings of the inner and outer discharge nozzles <b>6</b> and <b>7</b> are located close to a visual plane which is in common with the longitudinal axis <b>4</b> of the handpiece. By reference to this visual plane provision is also made that the two supply ducts <b>8</b> and <b>9</b> extending in parallel along the gripping member <b>3</b> under an angle with respect to the longitudinal axis <b>4</b> of the handpiece which differs from 90° provide axial crossing points with the common central axis <b>5</b> of the two discharge nozzles <b>6</b> and <b>7</b> at locations outside of this visual plane which by definition will allow a direct visual contact with the preparation field of the teeth during an abrasive dental treatment.

For optimizing this visual contact the closed surface of the gripping member <b>3</b> is therefore provided on an upper visual face <b>14</b> with a substantially concave curvature and on an underneath visual face <b>15</b> with a substantially convex curvature. The convex curvature of the underneath visual face <b>15</b> further extends to a concave curve <b>16</b> at a transition to the discharge openings of the inner and outer discharge nozzles <b>6</b> and <b>7</b>. By way of the illustrations in <figref idref="DRAWINGS">FIGS. 2 and 3</figref> it should be noted that the concave curve <b>16</b> is relatively shallow with the larger discharge angle of a nozzle piece <b>2</b>′ according to a second embodiment of the present invention and also extends much further than the concave curve <b>16</b> which is provided with a smaller discharge angle. As further illustrated in <figref idref="DRAWINGS">FIG. 4</figref> it should also be noted that the concave curvature of the upper visual face <b>14</b> provides an ergonomically designed finger resting surface by which an improved guidance of the handpiece may be obtained including a more optimized guidance of the working jet which is directed towards a preparation field of the teeth during an abrasive dental treatment. It should further be noted that by the thusly designed curvature of the closed surface of the gripping member <b>3</b> also a relatively short design length and design height of the entire nozzle piece <b>2</b> is obtained which will guarantee a perfect visual contact with the preparation field of the teeth.

For obtaining such a perfect visual contact for each nozzle piece <b>2</b> when fixed to the gripping sleeve <b>1</b> forming the head portion of the handpiece there is further provided a plug-in connection <b>18</b> for the two members which comprises for example a (see <figref idref="DRAWINGS">FIG. 5</figref>) groove and tongue connection which will secure a correct positioning of the visual plane with respect to the definite longitudinal axis <b>4</b> of the handpiece. It should be understood that instead of such a groove and tongue connection also differently designed safety means could be envisaged.